Unpaired Majorana fermions in quantum wires
arXiv:cond-mat/0010440 · doi:10.1070/1063-7869/44/10S/S29
Abstract
Certain one-dimensional Fermi systems have an energy gap in the bulk spectrum while boundary states are described by one Majorana operator per boundary point. A finite system of length $L$ possesses two ground states with an energy difference proportional to $\exp(-L/l_0)$ and different fermionic parities. Such systems can be used as qubits since they are intrinsically immune to decoherence. The property of a system to have boundary Majorana fermions is expressed as a condition on the bulk electron spectrum. The condition is satisfied in the presence of an arbitrary small energy gap induced by proximity of a 3-dimensional p-wave superconductor, provided that the normal spectrum has an odd number of Fermi points in each half of the Brillouin zone (each spin component counts separately).
16 pages, 5 figures, Latex and epsf, to be included in the proceedings of the Mesoscopic And Strongly Correlated Electron Systems conference (9-16 July 2000, Chernogolovka, Moscow Region, Russia), one reference added